Following what clang does (https:/llvm/llvm-project/blob/296a80102a9b72c3eda80558fb78a3ed8849b341/clang/lib/Driver/ToolChains/Darwin.cpp#L1661-L1678), allow allow SDKROOT to tell us where the Apple SDK lives so we don't have to invoke xcrun.

Previously we used the executables built the LLVM project but these
executables are difficult to run in a CI environment, they can
accidentally pollute global state, etc. In testing some of the possible
4-core machine environments for Azure this step would frequently cause
issues.

To assuage these future issues and hopefully make builds slightly more
self-contained, this commit changes to install from a tarball instead.
The tarball isn't provided by LLVM itself, but we use the offical LLVM
installer to extract itself and then we pack up the LLVM installation
directory into the tarball.

This is test specific to the NLL migrate mode which is irrelevant to -Z polonius.
It can't currently be encoded depending on migrate-mode and NLL/Polonius mode, so the NLL compare-mode also ignores it.

There is no difference between the NLL and Polonius outputs, and it manually tests NLLs.

…mpare mode

This is just a difference from the test construction, it's ignore-compare-mode-nll and manually checks migrate/nll over edition2015/2018.

This failure is because the `migrate2015` and `migrate2018`  revisions are ran with `-Zpolonius`. There is no actual difference in the errors output by NLLs and Polonius.

This is a test about turning the NLL feature gate on, ignored by the NLL compare-mode.

…re mode

Once again, the difference is in the test construction, it is ignored in compare-mode NLL and tested manually with revisions, and fails because the `migrate` revision is ran with `-Zpolonius`. There is no actual difference in the errors output by NLLs and Polonius.

2 of the 3 errors are "fixed by Polonius" 🎉

…Polonius

…r Polonius

…olonius

…or Polonius

Like "call-kills-loans", Polonius didn't know about some `killed` facts.

…ve-fn-1.rs for Polonius

…y loans

…ually check each outcome

Fixing assignments to projections made the Polonius output exactly the same as the NLL one.

In `configure.py`, using the `o` function creates an enable/disable
boolean setting, and writes `true` or `false` in `config.toml`. However,
rustbuild is expecting to parse a `u32` debuginfo level. We can change
to the `v` function to have the options require a value.

… r=alexcrichton

Add binary dependencies to dep-info files

I'm not sure about the lack of incremental-tracking here, but since I'm pretty sure this runs on every compile anyway it might not matter? If there's a better place/way to get at the information I want, I'm happy to refactor the code to match.

r? @alexcrichton

Polonius: fix some cases of `killed` fact generation, and most of the `ui` test suite

Since basic Polonius functionality was re-enabled by @matthewjasper in rust-lang#54468, some tests were still failing in the polonius compare-mode.

This PR fixes all but one test in the `ui` suite by:
- fixing some bugs in the fact generation code, related to the `killed` relation: Polonius would incorrectly reject some NLL-accepted code, because of these missing `killed` facts.
- ignoring some tests in the polonius compare-mode: a lot of those manually test the NLL or migrate mode, and the failures were mostly artifacts of the test revisions, e.g. that `-Z polonius` requires full NLLs. Some others were also both failing with NLL and succeeding with Polonius, which we can't encode in tests at the moment.
- blessing the output of some tests: whenever Polonius and NLL have basically the same errors, except for diagnostics differences, the Polonius output is blessed. Whenever we've advanced into a less experimental phase, we'll want to revisit these cases (much like we did on the NLL test suite last year) to specifically work on diagnostics.

Fact generation changes:
- we now kill loans on the destination place of `Call` terminators
- we now kill loans on the locals destroyed by `StorageDead`
- we now also handle assignments to projections: killing the loans on a either a deref-ed local, or the ones whose `borrowed_place` conflicts with the current place.

One failing test remains: an overflow during fact generation, on a case of polymorphic recursion (and which I'll continue investigating later).

This adds some tests for the fact generation changes, with some simple Polonius cases similar to the existing smoke tests, but also for some cases encountered in the wild (in the `rand` crate for example).

A more detailed write-up is available [here](https://hackmd.io/CjYB0fs4Q9CweyeTdKWyEg?view) with an explanation for each test failure, the steps taken to resolve it (as a commit in the current PR), NLL and Polonius outputs (and diff), etc.

Since they've worked on this before, and we've discussed some of these failures together:

r? @matthewjasper

…r=pietroalbini

ci: Install clang on Windows through tarballs

Previously we used the executables built the LLVM project but these
executables are difficult to run in a CI environment, they can
accidentally pollute global state, etc. In testing some of the possible
4-core machine environments for Azure this step would frequently cause
issues.

To assuage these future issues and hopefully make builds slightly more
self-contained, this commit changes to install from a tarball instead.
The tarball isn't provided by LLVM itself, but we use the offical LLVM
installer to extract itself and then we pack up the LLVM installation
directory into the tarball.

Add riscv32i-unknown-none-elf target

This target is likely to be useful for constrained FPGA soft-cores, such as picorv32 and HeavyX.

…xcrichton

add support for hexagon-unknown-linux-musl

Don't link mcjit/interpreter LLVM components

We don't use these. Drop related unused ExecutionEngine header uses.

As some drive-by cleanup drop the unused `EnableARMEHABI` global and remove an outdated version check for the hexagon component.

r? @alexcrichton

cleanup: Remove `extern crate serialize as rustc_serialize`s

Support SDKROOT env var on iOS

Following what clang does (https:/llvm/llvm-project/blob/296a80102a9b72c3eda80558fb78a3ed8849b341/clang/lib/Driver/ToolChains/Darwin.cpp#L1661-L1678), allow allow SDKROOT to tell us where the Apple SDK lives so we don't have to invoke xcrun.

Replaces rust-lang#62551.

…ulacrum

Require a value for configure --debuginfo-level

In `configure.py`, using the `o` function creates an enable/disable
boolean setting, and writes `true` or `false` in `config.toml`. However,
rustbuild is expecting to parse a `u32` debuginfo level. We can change
to the `v` function to have the options require a value.